A plan hatched last month has paid off for South Australian filly Miss Gunpowder in a Group Two win at Caulfield.

Miss Gunpowder is unbeaten in three starts in Adelaide but in planning ahead trainer Phillip Stokes brought the filly to Melbourne for a Caulfield race last month.

Stokes said the trip was beneficial to the daughter of Pendragon which took out the Thousand Guineas Prelude (1400m) on Saturday.

Under Craig Williams, Miss Gunpowder, the $4.20 favourite, scored a length win from Payroll ($41) with Jameka ($9.50) a long head away third.

"She travelled over well, better than last time," Stokes said.

"That was the secret, we do that for a lot of our horses.

"She stays through now."

Miss Gunpowder will now head to the Group One Thousand Guineas (1600m) at Caulfield on October 10 for which she is the $5 second favourite behind the $4.60 top choice Stay With Me.

Stokes said he had every confidence in the filly handling the extra 200m of the Thousand Guineas.

"We had her very fit and it's a matter of keeping her together for another two weeks," Stokes said.

"The 1600 metres should suit and she handles the track.

"She's got a pedigree that suggests she should get it."

Williams said it was too difficult to get off a filly that has won the Prelude two weeks before the main event.

He thinks the filly will handle the extra ground.

Williams said a mid-race move by Jimmy Cassidy on the runner-up Payroll had turned the race into a stamina test.

"Yes she's still got a question mark," Williams said.

"Because it wasn't a sit and sprint, but a bit of a staying test, I think if she holds that form and draws a barrier, she'll be able to hold a position without doing any work.

"I'm very confident about her going forward to the Thousand Guineas."